Above link indicate that following equations are used to calculate Normal Burst and Extended Burst in CAR.
normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
extended burst = 2 * normal burst
following example is also from same webpage but I am unable to understand how Normal burst is calculated and why extended burst is not 2*normal burst.
All World Wide Web traffic is sent. However, the MPLS experimental field for web traffic that conforms to the first rate policy is set to 5. For nonconforming traffic, the IP precedence is set to 0 (best effort). See the following commands in the example:
rate-limit input rate-limit access-group 101 20000000 24000 32000 conform-action
set-mpls-exp-transmit 5 exceed-action set-mpls-exp-transmit 0
access-list 101 permit tcp any any eq www